key holes

Anything that un-stabilizes the projectile.
For hand-loaders, its usually too long of a projectile going too slow in fps for the rifle twist.
 
Trying to shoot too long of a bullet for the twist of the barrel, like trying to shoot 75gr bullets out of 14 twist barrel or as as DAA says anything in the barrel that will upset the rotation of the bullet

Or something stupid, I bought a beautiful Epps customized MK-4 Enfield and everything keyholed with it, I even re crowned it and didn't realize it was a 35-303, not the original 303 Brit. The barrel was still marked 303. 35-303's shot beautifully.
 
Originally Posted By: DAAToo dirty or a shot out barrel the next most likely.

- DAA

Yup. Both my .220 Swift as well as my .17 Rem would print perfect keyholes on the target with a shot out barrel.
 
I bought an 1889 Marlin in .32-20. It came from a sheepherder in Montana. It was in rough shape when I got it. Cleaned the barrel, not good. Cleaned some more and still key holed every bullet that I shot. Some were perfect key holes and others were just an out of round hole.

Ten years later, new wood, a few hand made screws, and a stainless liner and she shoots like a dream. You can see the liner from the chamber and extractor cut, but the muzzle end is "blended" pretty well.

Since the barrel and magazine had been cut down, incorrect rear sight and wood in terrible shape... I don't believe I wrecked any collector value. It will never leave my house anyway !
 
Lead free bullets are longer than the same weight lead bullets are. So many of the smaller caliber rifles that have slow twist barrels you have to shoot lighter bullets.
 
Originally Posted By: colsonWhat causes a rifle to key hole? Never had this problem before.

You didn't really say, but are you getting keyholes from the exact same bullet that once shot perfectly fine in your gun, or did you change to a different bullet and you are now getting keyholes??
 
I just bought a 257 roberts from a gun show. I did run a couple patches down the barrel then went to shoot. Key hole was what I got. Have been cleaning with hoppies #9 and a brass brush today, and still getting black and blue patches started after reading the first replies around 8 this morning. Hope this is the problem.
 
I have seen two barrels key hole that were extremely dirty and full of copper, like a gold plated barrel inside.

Rusted barrels will key hole bullets.

Barrel could be shot out, or bullets too long for the twist rate.
 
Thank you all for the replies, very helpful. Measured the twist, and got 1-14. Think this is to slow for the 120 factory partitions that I got to shoot. Any bullet weight suggestions?
 
1*10 twists were put on Ruger, Rem, and Win. Yours must be a custom rifle to come up with a 14 twist, intended for light bullets.

I think that you should Re measure your twist rate with a brand new brush on a cleaning rod. If it comes up to 14 twist again, then you should go to the Berger Bullet site, and calculate the max bullet length that will stabilize in your barrel. It is very possible that you are only able to shoot 75g bullets that are meant for varmints.

Special twist rates should be stamped on the barrel.

Also, get some Flitz and scrub that barrel.
 
Its strange, but I have a barrel blank in 25 caliber with a 14 twist setting in my closet now. I had no idea why the odd twist rate, maybe it was a fad to have a 25 cal to shoot really light bullets, IDK? Someone wants it,I'll make you a deal.
 
The original model 99 250-3000 savages were twisted at 1-14 to get the 60-70's up to the magic 3000fps. Have played with a few that would stabilize up to the 87 Hornady. After that no go.
 
Lots of guys order barrel twist rates according to the bullets they like to shoot. A 14T is going to have a lot less pressure than a 9T, more speed is the result.

A 25/06 with a 14T will shoot the 85g Speer flat base at some unbelievable speeds, 3600+ would be a start with R#19, Win case, win primer.

Sounds like a great candidate for a rock chuck and coyote rifle!
 
A number of years ago I was preparing to go to Africa on a plains game hunt. Planning to take my 7mm RUM, I started working up a load for it. I started with the Barnes 175 gr TSX. Now, my rifle has 1:9.5 twist and they recommend 1:9 or faster in order to stabilize the bullet. I called Barnes, talked to them about it and decided to try a few.

They definitely key holed so I backed down to the 160 gr Barnes TSX and my groups went to less than an inch at 100 yards.

That has been my only experience with key holing and I definitely learned a lesson with that project.
 
Thank you all for the comments, and suggestions. I measered it again, and it is definitely a 14 twist. I was wanting the 257 roberts as an antelope gun. Any suggestions on a decent bullet?
 
87gr Speer Hotcore, shot well in my 250-3000. I also shot 75gr Barnes "X" bullets well. Now if someone would make a 100gr Round Nose for those old 14 twist Savages they'd sell like hotcake to about a dozen guys that still think it is a great deer rifle(me included). I built a 25-204(257 Kimber) to match original factory 250-3000 and 257 Roberts ballistics, 87gr bullets at 3000 fps and I twisted it 1-10 and shoot 100gr Partitions at 2800+ fps.
 
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